84 BMlletin of Laboratories of Denison University [Voi. xi. 
to the point of complete fusion. The result has been local 
thickening of the acid rocks and their conversion into quartzites, 
hornblendic schists, gneisses and finally granite. This last stage 
in the metamorphism has been attained by the old sedimen- 
taries in the Limitar range proper while to the north and south 
the place immediately below the lime is occupied by hornblendic 
schists with gneissic bands and veins of diorite. Passing south 
to the next centre of eruption (in the Socorros) the rock is sim- 
ply a quartzite. At various times the theory has been advanced 
that granite is properly speaking always protogene and conse- 
quently that a metamorphic origin is impossible. But aside 
from the strong testimony from analogy in the present case, 
there occurs about half way from the base of the Limitar to the 
lower surface of the lime a band of limestone included in the 
granite. This band is about eighteen inches wide and contains, 
in spite of high metamorphism, some fossil remains, proving 
conclusively the sedimentary nature of the beds from which the 
granite has been derived. Below, the granite passes into gneiss 
and this into hornblendic schist both the latter being broken by 
diorite. The writer has attempted to show on the basis of the 
conditions on the north shore of lake Superior, that diorite is 
essentially paragenetic and not an independent intrusive. The 
evidence of the region in question is strongly in favor of this 
conclusion for the diorites all assimilate closely to the gneisses 
in which they solely occur. 
Seen from the south, our volcano appears as a broad-based 
cone from which skeleton ridges extend to the north-west and 
south. The entire eastern base is composed of the acid series 
just described, most characteristic being the red coarse granite 
with large quartz grains and sparsely and crudely mingled horn- 
blende. Even at a great distance from the south one can de- 
tect the broad light stripe of obliquely tilted limestone where it 
is exposed by some vast eruptive outburst which not only tore 
open the very vitals of the mountain but plowed an enormous 
furrow across the lime and thus made good its escape to the 
south and east. Little is left to show of this flow but the 
eroded edge of the lime to the north and the tilted and scattered 
